Feathers Inspire Fade-Free Paint

When pores on a bird’s feathers flock together, they give Ivy League researchers an idea for paint that never fades.

A group of researchers at the Harvard School of Engineering and Applied Sciences say that creating nanostructured capsules that recreate bird feathers could lead to coatings and LED displays that never lose their hue.

Bird feathers have "structural color," meaning the color is created "when an object's very nanostructure amplifies a specific wavelength," whereas paints and dyes absorb light, the researchers explain.

Pigment in Pore Patterns

Brightly colored bird feathers have tiny pores that are spaced in just the right way to reflect the color. If this pore formation was destroyed, the color would be gone.

Jin-Gyu Park via seas.harvard.edu

Researchers want to use manmade materials to imitate pores on bird feathers, hoping to recreate the everlasting color.

Ipso facto, recreating this pore pattern in a different material would produce the same color.

Since some of the structural colors found in nature can last as long as the object, imitating it in manmade materials could result in color that never fades.

"Most color you get in paints, coatings or cosmetics, even, comes from the selective absorption and reflection of light," said Vinothan N. Manoharan, who led a team of Harvard researchers on this project.

"What that means is that the material is absorbing some energy, and that means that over time, the material will fade," Manoharan said.

Taking it to the Lab

The researchers worked to give manmade materials structural color—no easy task, since it usually requires molecules with a very specific crystalline pattern.

However, one bird in particular, the cotinga, has pores that lack a regular order, making it a prime target to mimic.

The team created a system where microcapsules are filled with a disordered solution of smaller particles suspended in water. The microcapsules shrink as they dry, bringer the particles closer together, until they eventually are spaced at just the right distance to give off the reflected color from the capsule.

The capsules will change to different colors the more they shrink, the researchers say. Being able to tune these color capsules could lead to a new spectrum of paints, according to Manoharan.

The project expands on 2009 research done at Yale University, which used dried aggregates of solid particles to recreate the cotinga's colors. Jin-Gyu Park did postdoctoral research on the project at Yale, and has now joined Manoharan's group.

The researchers' findings were published in February in the journal Angewandte Chemie.